Numerical modeling of the off-design performance of a transcritical CO2 two-phase ejector cycle

N. Lawrence, S. Elbel

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Ejector assisted cycles are known to offer significant COP and capacity improvements, especially for transcritical CO2 systems, when operated at the ejector design conditions. However, significant deviation from design conditions can lead to poor ejector and cycle performance. In this paper, a numerical model of a transcritical CO2 ejector cycle accounting for off-design ejector performance is developed. Experimental data from a CO2 ejector cycle, taken over a range of compressor speeds and ambient temperatures, is used to develop empirical models for the ejector and compressor. The evaporator in the system is a counterflow, microchannel heat exchanger and is simulated using a finite difference model capable of accounting for the heat transfer and pressure drop throughout the heat exchanger. The models of the individual components and cycle are validated using experimental data; good agreement between model and experiment is obtained.

Original languageEnglish (US)
Title of host publication12th IIR Gustav Lorentzen Natural Working Fluids Conference, GL 2016
PublisherInternational Institute of Refrigeration
Pages519-526
Number of pages8
ISBN (Electronic)9782362150180
DOIs
StatePublished - 2016
Event12th IIR Gustav Lorentzen Natural Working Fluids Conference, GL 2016 - Edinburgh, United Kingdom
Duration: Aug 21 2016Aug 24 2016

Publication series

NameRefrigeration Science and Technology
ISSN (Print)0151-1637

Other

Other12th IIR Gustav Lorentzen Natural Working Fluids Conference, GL 2016
CountryUnited Kingdom
CityEdinburgh
Period8/21/168/24/16

Keywords

  • Carbon dioxide
  • Numerical modeling
  • Off-design performance
  • Two-phase ejector

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering
  • Mechanical Engineering
  • Condensed Matter Physics

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